Airport noise has irritated Twin Cities residents for years, but now they may get answers about whether the roar of jets also damages their health.

For the first time, the agency that runs Minneapolis-St. Paul International Airport (MSP) last week asked national researchers to study the health effects of its noise.

"What I'm hoping is we're going to get some definitive science," said Dan Boivin, chairman of the Metropolitan Airports Commission (MAC).

The effort is the latest response to persistent concerns about airport noise from thousands of residents of Minneapolis, Eagan and Richfield who live in the flight paths. Since 2007, the commission has paid out $78 million to sound-proof homes and settle lawsuits by the cities and residents.

If studies reveal that noise may be more than annoying -- causing stress, high blood pressure or other ailments -- the commission will find itself in another tricky position.

Research so far on airport noise and health problems is unsettled but intriguing.

One older study surveyed 2,000 people around MSP and reported that "health measures were significantly worse in the neighborhoods exposed to commercial aircraft noise."

While limited, that study helped spur MSP officials to pursue more in-depth research, which likely will take years to complete.

"The studies that have been done have been so inconclusive," said Vern Wilcox, chairman of an airport noise panel. "We're saying if you're going to do this, let's do it right."

A resident of a neighborhood that recently experienced a spike in noise applauded the decision. "The cumulative affect of this ... is very definitely something that needs to be looked at," said Bob Friedman.

Noise and illness?

The MAC accepted the panel's recommendation to ask a group sponsored by the Federal Aviation Administration to include MSP in future research on the impact of airport noise on health.

The group is managed by the Massachusetts Institute of Technology and involves a dozen universities researching ways to reduce airplane noise and emissions. Stanford, Harvard, Purdue and Boston University are among participating schools.

The group in 2010 surveyed research around the world and noted that "recent studies have demonstrated a possible relationship between noise exposure, such as that caused by aircraft, and ... disease or infirmity."

It said some findings "support a possible role" between noise that disturbs sleep and high blood pressure.

The group in December launched a massive study on the potential effect of airport noise on the elderly. It will tap data on millions of Medicare recipients who live near 95 airports and compare them with similar people who live farther away. The study will try to isolate noise from other potential causes of disease, such as pollution or smoking.

The goal is to "evaluate the linkage between aviation-related noise and hospital admissions for cardiovascular disease."

Jonathan Levy of the Boston University School of Public Health, a lead investigator for the study, said it will consider whether "sleep deprivation and just the general stress of the noise can actually lead to elevated blood pressure."

Levy said MSP is among the airports included in the study, but the researchers also would consider doing more on MSP.

"If the airport were interested in a more detailed study, it's certainly something my research group ... would be interested in pursuing," he said.

Earlier suspicions

The older study on people living near Minneapolis-St. Paul airport was done by researchers from Oregon State University. Their findings were published in 2000 in the respected Journal of Environmental Health but received little attention until anti-noise activists recently alerted the airport about the study.

The researchers focused exclusively on MSP in part because of its network of noise monitors and proximity to neighborhoods with comparably affluent populations.

They compared neighborhoods exposed to high airport noise in Minneapolis, Bloomington, St. Paul and Eagan to neighborhoods without noise in Shoreview and Mounds View.

To avoid bias, researchers surveyed residents without first disclosing that they were studying the potential effects of airport noise.

Not only were health complaints worse in the noisy communities, "the greater the severity of the noise ... the worse the health measures were," the report said.

Researchers heard of "more headaches, higher stress, more insomnia," recalled Rebecca Donatelle, a former associate professor in the public health department who oversaw the work. "More studies need to be done."

Thorough research could take years. Since the Oregon State study, twice as many homes near MSP have been sound-proofed, and airlines have phased out some louder planes. But changing flight patterns recently have been blamed for more noise in some areas.

Prospects mulled

Airport officials acknowledge that they would face new questions if a link between airplane noise and health problems were ever established.

"If in fact it does show something, are you looking to get more remediation for homeowners?" asked Wilcox. "Are you looking to change the pattern of the airport so it doesn't affect health?"

"There are so many directions this could go," he said.

Boivin said court agreements that settled lawsuits over noise in exchange for sound-proofing closed the door on more litigation. He said federal approval would be needed to launch a new sound-proofing program.

Any program should apply nationwide, Boivin said.

"I certainly don't want to be the only airport and then be put at an economic disadvantage to other airports," he said.